Global NEST Journal

The aim of the study was to determine cadmium influence on the lead phytotoxicity to spring barley (Hordeum vulgare L.). The seedlings of H. vulgare were treated with single Pb (ranging from 0.1 to 100 mg l-1) and Pb mixture with Cd. Plant biomass production, physiological response, induction of oxidative damage and metals accumulation in roots and shoots were evaluated. Single Pb and under the presence of cadmium impaired the growth of H. vulgare, altered the content of photosynthetic pigments and induced lipid peroxidation. The addition of Cd to the Pb treatments has led to additive or synergistic effects on H. vulgare shoot and root dry weight, oxidative damage and increased bioaccumulation. The interactive effect of these metals on the content of photosynthetic pigments was concentration range dependent. Additivity was detected when H. vulgare were exposed to low concentrations of Cd and Pb and high concentrations of these metals had lower than additive effect.

Currently, the ecosystem is being damaged in many rivers and subsequently the fish species living there are also facing decline or even extinction. This situation urges to model the habitat and to design suitable restoration strategies in order to increase the capabilities of ecological modeling. In this paper, we proposed a numerical model to assess the ecosystem habitat situation and investigated the impacts of two ecological restorations strategies for the target fish species. The model includes a hydrodynamic model, a habitat model and habitat restoration schemes. The hydrodynamic model simulated the flow properties while sediments in the riverbed were also surveyed. Based on these parameters and fish preference curves, the habitat suitability indices were calculated. In order to analyze the river habitat quality, the weighted usable areas and overall suitability index were also calculated and the effects of the restoration strategies on selected fish species (Freshwater Reeves shad - Tenualosa reevesii) in the Chin-sha River were evaluated. The two ecological restoration strategies: addition of side-channel (scheme I) and river bank reconstruction (scheme II) enhanced the Freshwater Reeves shad habitat suitability level, with the high suitability index proportion increasing from 19.5% to 33.1% for scheme I and to 36.1% for scheme II. Based on the modelling results, we concluded that our numerical model could potentially provide suitable scenarios for successful fish habitat restoration.

Contaminants of emerging concern (CECs), such as pharmaceuticals and personal care products (PPCPs) and as endocrine disrupting compounds, have recently recognized as the next set of pollutants due to their toxic effects on human health and aquatic organisms at very low concentrations. One of effective methods to remove these emerging contaminants present in the aquatic environment is a membrane bioreactor (MBR). In this review, 27 CECs belonged to diverse categories of PPCPs were surveyed from the point of view of the removal efficiency by several types of MBR modules with various operational conditions, such as a type of MBR, hydraulic retention time and sludge retention time. As a result, this review provided the overall ranges in the removal efficiency of 27 CECs by different MBR filtrations and modules. Certain categories of PPCPs such as analgesics/anti-inflammatory drugs (acetaminophen and ibuprofen), steroids/hormones (estriol and testosterone) and stimulant (caffeine) have relatively higher removal rates, while antimicrobial agent (TCEP) is rarely removed in the different MBRs. For further implementation of CEC removal by a MBR system, physical characteristics/biological fate of a wide variety of CECs, individual/synergistic effects which may occur during MBR operation, and application of advanced MBR technologies should be studied.

Here the effectiveness of cation selective membranes, produced for divalent mercury (Hg2+) preconcetration from aqueous bodies, is examined. To this end, the behavior of PVC-based membranes, functionalized with dithizone for mercury complexation, is examined by means of Energy Dispersive X-ray Fluorescence (EDXRF) and total reflection - X-ray absorption near-edge structure (TXRF–XANES) techniques. In our previous works, we successfully immobilized dithizone on PVC-based thin film substrates, creating novel Hg-selective membranes, and identified the optimal experimental parameters affecting mercury sorption from water samples. Nonetheless, the question remains, to what extent dithizone is responsible for mercury complexation on the membrane surface, or it just improves the membrane’s active surface area thus simply improving the adsorptive effect. Using the EDXRF technique it appears that membranes functionalized with dithizone has a much higher efficiency (by up to threefold) in preconcetrating mercury from water matrices, compared to the non-functionalized membranes. Then, the membranes were also examined by means of TXRF–XANES and it was identified that indeed mercury-dithizone complex is produced on the membrane surface, which is responsible for the much higher mercury sorption, compared to the non-functionalized membranes. Also, the XANES mercury-dithizone spectrum is presented. Given polymer membrane simple manufacturing procedure and their low cost this study works towards establishing a new method for very low concentration mercury analysis (sub-ppb levels) as well as mercury collection from aqueous bodies, provided that the membranes are produced and used in large-scale routine works.